The long-range objectives of this research is to understand the distribution of positional information involved in embryonic axonal growth and synaptogenesis. The work is based on earlier studies in which anuran optic nerve axons penetrated the medulla oblongata and spinal cord following embryonic transplantation of the eye primordia. Proposed experiments will use autoradiographic, electrophysiological and ultrastructural techniques to study the growth and termination pattern of ectopic optic tracts following a variety of eye transplantations and surgical manipulations of the neural tube. These experiments are designed to: 1. determine the role played by neural tube polarity in the establishment of a stereotyped axonal projection; 2. examine the influence of tectal tissue on transplanted optic tract growth and termination; 3. explore previous suggestions that a rudimentary form of organization is maintained in the branching pattern of the transplanted optic tract; 4. explore abnormally penetrated spinal cords for fine structural evidence of anomalous optic nerve synapses. This research will be conducted on anuran (Rana pipiens) material. However, the results of these studies should provide insight into basic principles of vertebrate neural pathway development which may then be applied to the prevention and treatment of human neurological disorders.